I went down to the pawn shop a few days ago and saw a Mauser Kar98 for 240 dollars with a US armory stamp on it, it looks like a number of the rifles were captured by US and Russians, the wood was slightly damaged (looked like it had been dropped or the Nazi soldier was shot and landed on the stock of the rifle). It has the eagle with the swastika on the receiver.
I know that a lot of US soldiers took these rifles home as trophies, there are also a number of KAR98's with the swastika etched off or completely removed, I seen a few Serbian copies. I don't think I could deface a rifle because it is a piece of history, and is symbolic of me using the enemies gun. I think if we were in a situation where we were fighting against the Nazis and we picked up a Nazi weapon, we would not worry about removing a symbol but using the weapon to fight against the enemy.
However defacing/removing a symbol is not uncommon or unheard of either, it's strange in a way that people do not feel the same way about the Communist sickle/hammer as they do about the swastika. Many AK47's/SKS from communist countries bear the star with the sickle/hammer and are not defaced.
I think as long as it is for historical purposes and what not, it is fine, but not for Germany to start putting new weapons out with the swastika, that would be stupid.
You know the Japanese, before they were captured or would kill themselves, on the Arisaka rifle, they had a emblem of the "mum" (the imperial flower symbol), and the rifle was considered property of the emperor, before they were captured, they would take a file and try to destroy or deface the symbol as it was considered dishonorable for the Americans to have possession of the emperors property, these are highly valued war trophies today and even the Arisakas with the mum intact are highly valued compared to those that have been defaced. in 50 years, these weapons will be very hard to find.
But anyways, from a perspective, it is true that Adolf Hitler loved the KAR98 and highly despised the STG44, at least at first. The KAR98 while a great rifle, perhaps one of the best bolt action rifles in history, I think US had a large advantage by equipping soldiers with the M1 Carbine and M1 Garand being semi automatic. KAR98 probably made a better sniper rifle. The STG44 was developed in secret without Hitlers knowledge and he was not satisfied with it at first and by the time the Nazis were equipped with it, was already too late to make much of a difference. STG44's are pretty hard to find in the US although I have seen them appear in Africa in VERY small numbers, I wonder how they ended up in Africa anyways? I'd think finding ammo for it would be pretty hard.